Category discrimination by pigeons using five polymorphous features.
Pigeons can watch five uncorrelated cues at once, so learners can master complex categories without relying on a single feature.
01Research in Context
What this study did
Researchers taught eight pigeons to sort pictures into two groups.
Each picture had five visual cues, but no single cue told the bird the right group.
The birds had to watch all five cues at once to earn grain.
What they found
Seven of the eight birds learned the task.
Later, the team flipped one cue and the birds quickly adjusted.
The other four cues still guided choices, showing each cue kept its own power.
How this fits with other research
Tracey et al. (1974) showed pigeons lock onto the part of a picture that differs most.
Cohen et al. (1990) moved past that: birds can watch many uncorrelated parts at the same time.
Honig et al. (1988) found pigeons can group photos by place; the 1990 study adds that birds can juggle five abstract cues without choosing a favorite.
Zentall et al. (1975) saw mixed control when cues sit side-by-side; L et al. show clean control when each cue is reversed alone.
Why it matters
When you teach a child to sort "safe" versus "hot" items, use several small cues together.
If one cue later changes, the learner can adjust without dropping the other safety signs.
Try adding extra redundant cues early; later you can fade or flip one and the skill stays solid.
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02At a glance
03Original abstract
Eight pigeons were trained to discriminate between sets of color photographs of natural scenes. The scenes differed along five two-valued dimensions (site, weather, camera distance, camera orientation, and camera height), and all combinations of the feature values were used. One value of each dimension was designated as positive, and slides containing three or more positive feature values were members of the positive stimulus set. Thus, each feature had an equal, low, correlation with reinforcement, and all features had zero correlations with each other. Seven of the 8 pigeons learned this discrimination, and their responding came under the control of all five features. Within the positive and negative stimulus sets, response rates were higher to stimuli that contained more positive feature values. Once discrimination had been achieved, reversal training was given using a subset of the slides. In this subset, only a single feature was correlated with reinforcement. All pigeons learned this reversal successfully and generalized it to additional photographs with the same feature content. After reversal, the original reinforcement contingencies were reinstated, and training was continued using all the slides except those that had been used in reversal. Reversal generalized to these slides to some extent. Analysis of the response rates to individual slides showed that, compared with prereversal training, only the feature that had been subjected to reversal contingencies showed a reversed correlation with response rate. The remaining features showed the same correlation with response rate as they had before reversal training. Thus, reversal on some members of a category following category discrimination training led to generalization to stimuli within the category that were not involved in the reversal, but not to features that were not reversed. It is therefore inappropriate to refer to the pigeons as learning a concept.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.54-69